Did you take fundies though? Fundies is hands down the best skills class I've ever taken. The 2nd best class was a con ed sidemount course, but the instructor was a cave diver and had been through the GUE program as well. It went waaaaaaay beyond the curriculum. I'd say most of the con ed courses I've taken, with exception to rescue from two different agencies, were a waste of money.Couple years ago I was interested in GUE because I had thought it could teach me a few new tricks/ skills that would ultimately make me just that much more comfortable in the water.
That's it - in a nutshell - right there. Whatever comfort level you're at - GUE has the potential to make you just slightly more comfy. So does any scuba school, honestly.
With GUE, there is a high return on investment, and non GUE instructors should shoot for that high return on investment if their agency permits them.